Transmission apparatus

ABSTRACT

The present invention relates to a transmission apparatus ( 15 ) including at least one of a dividing unit ( 6 ) and a differential planetary gear unit ( 30 ), and a joint unit ( 20 ). A rotational power, which has been input to the transmission apparatus ( 15 ), is transmitted to the joint unit ( 20 ) via the dividing unit ( 6 ) or the differential planetary gear unit ( 30 ). A rotational power to be input to the joint unit ( 20 ) is smaller than the rotational power which has been input to the transmission apparatus ( 15 ), and the joint unit comprises a fluid coupling.

This application is a divisional application of U.S. Ser. No.10/505,010, filed Aug. 19, 2004, which is a national stage ofPCT/JP03/02083, filed Feb. 25, 2003.

TECHNICAL FIELD

The present invention relates to a transmission apparatus having adividing unit to which a rotational power from a drive unit istransmitted, a joint unit, and a first differential planetary gear unit,and specifically to a transmission apparatus used to rotate a fluidmachinery such as a turbo machinery by a drive unit such as a motor forsynchronizing a drive side and a driven side with each other, relievingan impact that occurs at starting/stopping or at changing in arotational speed, and achieving an efficient transmission of arotational power.

BACKGROUND ART

In a conventional apparatus shown in FIG. 22, an output shaft C4 of anelectric motor A1 serving as a drive source is connected to an inputside of a driven unit A2 such as a fluid machinery via a joint A22 andan output shaft C7. In this case, transmission of a rotational powerfrom the electric motor A1 is limited to a range in which the joint A22can transmit the rotational power.

At the same time, there is a need to transmit a rotational power beyondthe range in which the joint A22 can transmit the rotational power.

In order to meet such a need, as shown in FIGS. 23A and 23B, there hasbeen proposed a transmission apparatus A15 which distributes or dividesa rotational power that is input from a drive source A1.

According to the transmission apparatus A15 shown in FIGS. 23A and 23B,the rotational power from the drive source A1 is distributed to a powerline R1 and a power line R2 by a dividing unit 6, so that the rotationalpower below the transmission limit of a continuously variabletransmission A20 is distributed to the power line R1 and the residualrotational power is distributed to the power line R2.

The rotational powers divided by the dividing unit 6 are converged by adifferential planetary gear unit A30 disposed at an output side of thecontinuously variable transmission A20, so that the converged rotationalpower is transmitted to a driven unit A2 via a single output shaft 37.

With this structure, the rotational power beyond the transmission limitof the continuously variable transmission A20 can be transmitted to thedriven side.

However, the continuously variable transmission A20 shown in FIGS. 23Aand 23B employs a mechanism of a toroidal-type continuously variabletransmission (CVT). Since the toroidal-type CVT is of a contact type,there are limits to a maximum transmission power and a service life.Therefore, it is difficult to apply the toroidal-type CVT to a largeequipment which is required to transmit a large power, and to anindustrial machinery which is required to have a reliability.

Further, various kinds of vibrations and impacts, such as pulsation dueto power fluctuation, shock vibration at speed change, and torsionvibration of the output shaft, are transmitted or occur to an outputside of the toroidal-type CVT. Accordingly, the toroidal-type CVT, whichutilizes solid friction, is problematic in output fluctuation anddurability because of such vibrations and impacts.

In addition, another type of conventional transmission apparatus has thesame problems.

DISCLOSURE OF INVENTION

The present invention has been made in view of the above drawbacks. Itis therefore an object of the present invention to provide atransmission apparatus which can efficiently transmit a rotational powerbeyond a transmission limit of a joint unit, and can absorb variouskinds of vibrations and impacts, such as pulsation, shock vibration atspeed change, and torsion vibration of an output shaft, for therebyenabling an increase in service life and power transmission limit.

A transmission apparatus according to the present invention comprises:at least one of a dividing unit (6) and a differential planetary gearunit (30); and a joint unit (20); wherein a rotational power to betransmitted via the joint unit (20) is smaller than a rotational power(i.e., a rotational power of a drive unit) which has been input to thetransmission apparatus, and the joint unit (20) comprises a fluidcoupling.

In the transmission apparatus according to the present invention, therotational power which has been input to the transmission apparatus istransmitted to the dividing unit (6) via a single input shaft and isoutput to two rotating shafts, one of the two rotating shafts isconnected to one of two input shafts of the differential planetary gearunit (30), and the other of the two rotating shafts is connected to theother of the two input shafts of the differential planetary gear unit(30) via the fluid coupling (20).

FIGS. 24A through 24D schematically illustrate the manner in which apower is transmitted from a drive unit A1 to a driven unit A2. For,example, in FIG. 24A, a power P from the drive unit A1 is divided by adividing unit (distribution gears) 6. A power P1, which is one of thedivided powers, is transmitted to a differential planetary gear unit A30via a power line R1. A power P2, which is the other of the dividedpowers, is transmitted to the differential planetary gear unit A30 via acontinuously variable transmission A20 and a power line R2. The power P1and the power P2 are joined together again in the differential planetarygear unit A30 and then transmitted to the driven unit A2.

FIGS. 24A and 24B illustrate the manner of power distribution, and FIGS.24C and 24D illustrate the manner of power circulation. In FIGS. 24Athrough 24D, magnitude of the power flow due to action of thedifferential planetary gear unit A30 is expressed by a width of a whitearrow. The power distribution means the manner in which the power fromthe input side is divided by the distribution gears and the dividedpowers are transmitted through two paths and then joined together by thedifferential planetary gear to flow into the output side. The powertransmitted through one of two distribution shafts is larger than thepower transmitted through the other of the distribution shafts. On theother hand, the power circulation means the manner in which the powerfrom the input side flows only into one of the distribution gears andflows into the output side via the differential planetary gear(hereinafter, a shaft through which the power is transmitted will bereferred to as a shaft A). Specifically, as shown in FIGS. 24C and 24D,there exists a power flow circulating in the order of the differentialplanetary gear→the distribution gears→the continuously variabletransmission→the differential planetary gear. In this case, the powersflowing through the shaft A are joined together and the joined powerbecomes larger than the input power. The power flowing through the othershaft becomes small and its flow direction is reversed.

FIGS. 24B and 24C schematically illustrate the power transmission mannerof the present invention. The magnitude of the power flow of the powerline R2 passing through the continuously variable transmission A20 issmaller than the input power.

Specifically, “the rotational power to be transmitted via the joint unit(20) is smaller than the rotational power which has been input to thetransmission apparatus”, which is an essential element of the presentinvention, means the manner in which the magnitude of the power flow ofthe power line R2 passing through the continuously variable transmissionA20 is smaller than the input power, as shown in FIGS. 24B and 24C. Thepresent invention uses a fluid coupling as the continuously variabletransmission.

It is preferable that the fluid coupling comprises a variable-speedfluid coupling. According to the transmission apparatus of the presentinvention having such a structure, the rotational power beyond thetransmission limit of the joint unit is not input to the joint unit, andhence the rotational power can be transmitted efficiently. Further, thefluid coupling can absorb various kinds of vibrations and impacts, suchas pulsation of the input rotational power, shock due to speed change,and torsion vibration of the shaft, thus enabling a smooth transmissionof the power.

In the transmission apparatus according to the present invention, therotational power which has been input to the transmission apparatus istransmitted to the dividing unit (6) via a single input shaft (15 a) andis output to two rotating shafts (4, 9), one (9) of the two rotatingshafts (4, 9) is connected to one (13) of two input shafts (13, 5) ofthe differential planetary gear unit (30), and the other (4) of the tworotating shafts (4, 9) is connected to the other (5) of the two inputshafts (13, 5) of the differential planetary gear unit (30) via thefluid coupling (20).

With such a structure, even if the power, which is input to thetransmission apparatus, exceeds the transmission limit of the jointunit, the input power is divided into two by the dividing unit, so thatone of the divided powers, which is below the transmission limit, isdistributed to the fluid coupling and the other is directly distributedto the differential planetary gear unit. Accordingly, the transmissionapparatus can transmit the power that is beyond the transmission limitof the fluid coupling.

In the transmission apparatus according to the present invention, therotational power which has been input to the transmission apparatus istransmitted to the differential planetary gear unit (30B) via a singleinput shaft (15 b) (of the dividing unit) and is transmitted to twooutput shafts (13 b, 4 b) of the differential planetary gear unit (30B),one (a direct-coupling shaft 13 b) of the two output shafts of thedifferential planetary gear unit (30B) is connected to one (9 b) of twoinput shafts of a converging unit (6B), and the other (4 b) of the twooutput shafts of the differential planetary gear unit (30B) is connectedto the other (37 b) of the two input shafts of the converging unit (6B)via the fluid coupling (20).

According to the transmission apparatus of the present invention havingsuch a structure, the input power is divided into two by thedifferential planetary gear unit, so that one of the divided powers,which is below the transmission limit, is distributed to the fluidcoupling and the other is directly distributed to the dividing unit.Accordingly, the transmission apparatus can transmit the power that isbeyond the transmission limit of the fluid coupling.

It is preferable that a gear unit (52 d, 53 d) having a speed-increasinggear and a speed-decreasing gear is provided on at least one of an inputshaft (9, 5) and an output shaft (37 d) of the differential planetarygear unit.

With such a structure, while keeping a rotational speed or a torque thatis input to the transmission apparatus constant, the rotational speed orthe torque that is output to the driven unit can be freely adjusted toan efficient value.

A transmission apparatus according to the present invention comprises: adividing unit to which a rotational power from a drive unit istransmitted; a joint unit; and a first differential planetary gear unit;wherein one rotational power to be transmitted via the joint unit issmaller than the other rotational power, and the joint unit comprises anelectric motor and a second differential planetary gear unit.

A transmission apparatus according to the present invention comprises:at least one of a dividing unit and a first differential planetary gearunit; and a joint unit; wherein a rotational power from a drive unit isdivided into at least two rotational powers by the dividing unit or thefirst differential planetary gear unit, one of the rotational powers isinput to the joint unit, the rotational power to be input to the jointunit is smaller than the other of the rotational powers, and the jointunit comprises an electric motor and a second differential planetarygear unit.

In the transmission apparatus according to the present invention, therotational power from the drive unit is transmitted to the dividing unitvia a single input shaft of the dividing unit and is output from thedividing unit to two rotating shafts, one of the two rotating shafts isconnected to one of two input shafts of the first differential planetarygear unit, and the other of the two rotating shafts is connected to theother of the two input shafts of the first differential planetary gearunit.

In the transmission apparatus according to the present invention, therotational power from the drive unit is transmitted to a single inputshaft of the first differential planetary gear unit, one of two outputshafts of the first differential planetary gear unit is connected to oneof two input shafts of a converging unit, and the other of the twooutput shafts of the first differential planetary gear unit is connectedto the other of the two input shafts of the converging unit via thesecond differential planetary gear unit.

In the transmission apparatus according to the present invention, thesecond differential planetary gear unit has a single-pinion-typestructure in which one planetary gear is arranged in a radial directionand one or more planetary gears are arranged in a circumferentialdirection in a region between a sun gear and a ring gear, and each ofthe drive unit, the electric motor, and a load is directly connected toany one of an input shaft, an output shaft, and a speed-change shaft.

Accordingly, since the power from the drive unit is transmitted to theload without passing through the joint unit, a capacity of the jointunit can be small even in a case of operating a large machinery.Further, since the joint unit comprises the differential planetary gearunit having no frictional part but having a mechanically couplingstructure, the long service life can be achieved and the transmissionlimit can become sufficiently high.

In order to clarify the effect of the present invention, first, therewill be illustrated a flow of the rotational power transmitted by acombination of the dividing unit 6, a speed-change device, i.e., thejoint unit R, and the differential planetary gear unit G, with referenceto FIGS. 18 through 21. The dividing unit 6 is connected to an inputshaft I. One of power flows that are output from the dividing unit 6 isinput to a shaft R2 of the differential planetary gear unit G throughthe joint unit R, and the other is input to another shaft R1 of thedifferential planetary gear unit G. The power flows are then output froman output shaft O.

When the power flow, which is represented by a reference sign P, of theinput shaft I is divided into P1 and P2 by the dividing unit 6, thepower flow of the output shaft is P on the assumption that there is noloss. Magnitude of the power flow is expressed by a width of a whitearrow.

It is preferable that the power flow passing through the joint unit R isas small as possible, and hence it can be said that the manner shown inFIGS. 19 and 20 is preferable. Specifically, “the rotational power to betransmitted via the joint unit is smaller than the rotational powerwhich has been input to the transmission apparatus”, which is anessential element of the present invention, means the manner in whichthe magnitude of the power flow of the power line R2 passing through thejoint unit R is smaller than the input power, as shown in FIGS. 19 and20.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view showing a transmission apparatus according to a firstembodiment of the present invention;

FIG. 2 is a block diagram schematically showing the transmissionapparatus in FIG. 1;

FIG. 3 is a view showing a fluid coupling having an operating device(scoop tube) disposed at a power input side;

FIG. 4 is a view showing the fluid coupling having the operating device(scoop tube) disposed at a power output side;

FIG. 5 is a view showing a differential planetary gear unit;

FIG. 6 is a view showing a transmission apparatus according to a secondembodiment of the present invention;

FIG. 7 is a view showing a transmission apparatus according to a thirdembodiment of the present invention;

FIG. 8 is a view showing a transmission apparatus according to a fourthembodiment of the present invention;

FIG. 9 is a view showing a transmission apparatus according to a fifthembodiment of the present invention;

FIG. 10 is a view showing a transmission apparatus according to a sixthembodiment of the present invention;

FIG. 11 is a view showing a transmission apparatus according to aseventh embodiment of the present invention;

FIG. 12 is a view illustrating a transmission apparatus according to aneighth embodiment of the present invention;

FIG. 13 is a view illustrating a transmission apparatus according to aninth embodiment of the present invention;

FIG. 14 is a view illustrating a transmission apparatus according to atenth embodiment of the present invention;

FIG. 15 is a view illustrating a transmission apparatus according to aneleventh embodiment of the present invention;

FIG. 16 is a flow chart illustrating an operation of the eleventhembodiment shown in FIG. 15;

FIG. 17 is a view illustrating a twelfth embodiment of the presentinvention;

FIG. 18 is a view illustrating a power flow of a joint unit distributedby a dividing unit;

FIG. 19 is a view illustrating another power flow of the joint unitdistributed by the dividing unit;

FIG. 20 is a view illustrating still another power flow of the jointunit distributed by the dividing unit;

FIG. 21 is a view illustrating still another power flow of the jointunit distributed by the dividing unit;

FIG. 22 is a block diagram illustrating a relationship between a drivesource, a fluid coupling, and a driven unit of a conventional apparatus;

FIG. 23A is a view illustrating a conventional transmission apparatus;

FIG. 23B is a view showing a power-dividing unit, a continuouslyvariable transmission, and a differential planetary gear unit of aconventionally proposed transmission apparatus; and

FIGS. 24A through 24D are schematic views illustrating the manner inwhich a power is transmitted from a drive unit to a driven unit.

BEST MODE FOR CARRYING OUT THE INVENTION

FIGS. 1 and 2 show a first embodiment of the present invention. FIG. 1is a schematic view showing a detailed structure of a transmissionapparatus of the present invention, and FIG. 2 is a block diagramschematically showing the transmission apparatus. Those parts which aredenoted by the same reference numerals as those of the conventionalapparatus shown FIG. 23 have identical structure and function.

In FIGS. 1 and 2, a transmission apparatus 15 is disposed between amotor A1 (expressed as a drive unit A1 in FIG. 1) serving as a drivesource and a fluid machinery A2 (expressed as a rotary machine A2 inFIG. 1) serving as a driven unit. The transmission apparatus 15 iscoupled to the motor A1 and the fluid machinery A2 via an input-sideclutch 3 and an output-side clutch 39.

The transmission apparatus 15 comprises a power-dividing unit 6, a fluidcoupling 20 for speed change, and a differential planetary gear unit 30,each of which serves as an essential part thereof.

The power-dividing unit 6 divides a rotational power of a rotating inputshaft 15 a connected to the input-side clutch 3 into two and distributesthe divided rotational powers to a rotating shaft 4, which is directlyconnected to the rotating input shaft 15 a, and to a rotating shaft 9via gears 7 and 8. A power line via the rotating shaft 4 serves as apower line R1, and a power line via the rotating shaft 9 serves as apower line R2. There are two cases in the direction of the powertransmission of the power line R1: One is that the power is transmittedfrom the rotating shaft 4 to the rotating shaft 5 via the fluid coupling20, and the other is that the power is transmitted from the rotatingshaft 5 to the rotating shaft 4 via the fluid coupling 20.

In the latter case, the fluid coupling 20 comprises an operating device22, a drive pump 26, and a driven turbine 24, and is constructed so asto transmit the power from the rotating shaft 5 to the rotating shaft 4.

The differential planetary gear unit 30 comprises a sun gear 31, piniongears 33, and a ring gear 35, as with a known structure. The sun gear 31which is directly connected to the rotating shaft 5, and a carrier 13which couples the rotating shaft 9 to the pinion gears 33 via a gear 12serve as input shafts, respectively, and the ring gear 35 serves as anoutput shaft. The ring gear 35 is connected to the fluid machinery A2via a rotating shaft 37 and the output-side clutch 39.

FIG. 3 shows the fluid coupling 20 having a structure in which a poweraspect (i.e., a rotational speed and a torque) to be transmitted to therotating shaft 4 directly connected to the turbine 24 is operated by theoperating device 22 which controls a rotational speed of the pump 26directly connected to the rotating shaft 5. FIG. 4 shows a structure inwhich the power aspect to be transmitted to the rotating shaft 5 isoperated by the operating device 22 which controls a circulating flowbetween the pump 26, which is directly connected to the rotating shaft4, and the turbine 24.

The fluid coupling 20 shown in FIG. 3 is the type that is used in thetransmission apparatus 15 of the first embodiment.

FIG. 5 shows a structure of the differential planetary gear unit 30. Inthe first embodiment, the sun gear 31 connected to the rotating shaft 5serves as the input shaft, and the carrier 13 rotatably supporting thepinion gears 33 and connected to the rotating shaft 9 also serves as theinput shaft. The ring gear 35 serves as the output shaft. It is knownthat the differential planetary gear unit has six permutations ofinput-output patterns that are made by a combination of the sun gear 31,the carrier 13, and the ring gear 35. Specifically, the number ofpermutations of the elements comprising the sun gear 31, the carrier 13,and the ring gear 35, two input shafts (i.e., the direct-coupling shaft9 (see FIG. 2) without passing through the speed-change device and thespeed-change shaft 5 passing through the speed-change device), and oneoutput shaft 37 of the differential planetary gear unit is six given by3.

Operation of the transmission apparatus 15 having the above-mentionedstructure will be described below.

First, a rotational power having a torque Ti and a rotational speed ωiis transmitted from the motor A1 serving as a drive source to therotating input shaft 15 a of the transmission apparatus 15 via theinput-side clutch 3. The rotating input shaft 15 a transmits therotational power to the power-dividing unit 6. The power-dividing unit 6distributes the rotational power to the rotating shaft 4 of the powerline R1 and the rotating shaft 9 of the power line R2. At this time, thedistribution of the rotational power to the rotating shaft 4 is limitedto such a degree that a torque is below a transmission limit defined byan absorption capability of the fluid coupling 20 while a rotationalspeed is ωi. The rotational power distributed to the rotating shaft 9has the rotational speed ωi and a residual torque if the power-dividingunit 6 a has a gear ratio of 1. It is preferable that the torque to bedistributed to the fluid coupling 20 is selected such that an efficienttransmission is achieved while the torque is kept below the transmissionlimit.

The rotational power of the rotating shaft 9 is transmitted to thecarrier 13 via the gear 12. On the other hand, the rotational power ofthe rotating shaft 4 is changed in speed and torque by the fluidcoupling 20 and transmitted to the sun gear 31 of the differentialplanetary gear unit 30.

The rotational powers transmitted to the carrier 13 and the sun gear 31are transmitted from the ring gear 35 to the fluid machinery A2 via therotating shaft 37 and the output-side clutch 39. At this time, therotational power transmitted to the fluid machinery A2 has a rotationalspeed ω0 and a torque To. Assuming that there is no power transmissionloss in the transmission apparatus 15, the following relation holds:ωi×Ti=ωo×To

In this manner, the rotational power from the motor A1 is divided intotwo and distributed to the power line R1 passing through the fluidcoupling 20 and the branched power line R2, and the divided rotationalpowers are joined together again by the differential planetary gear unit30, so that the transmission apparatus 15 transmits the rotational powerthat is beyond the rotational power limit of the fluid coupling 20.

FIG. 6 shows a second embodiment of the present invention. Those partswhich are different from those of the first embodiment shown in FIGS. 1and 2 will be mainly described below. Those parts which are denoted bythe same reference numerals as those shown FIG. 1 have identicalstructure and function.

In FIG. 6, a transmission apparatus 15B is disposed between a motor A1(expressed as a drive unit A1 in FIG. 6) serving as a drive source and afluid machinery A2 (expressed as a rotary machine A2 in FIG. 6) servingas a driven unit. The transmission apparatus 15B is coupled to the motorA1 and the fluid machinery A2 via an input-side clutch 3 and anoutput-side clutch 39.

The transmission apparatus 15B comprises a differential planetary gearunit 30B, a fluid coupling 20 for speed change, and a power convergingunit 6B, each of which serves as an essential part thereof.

The differential planetary gear unit 30B comprises a sun gear 31 b,pinion gears 33 b, and a ring gear 35 b, as with a known structure. Thering gear 35 b directly connected to a rotating shaft 15 b serves as aninput shaft, and a carrier 13 b connected to a rotating shaft 9 b and arotating shaft 4 b connected to the sun gear 31 b serve as outputshafts, respectively.

The fluid coupling 20 comprises an operating device 22, a drive pump 26,and a driven turbine 24, and is constructed so as to transmit the powerfrom the rotating shaft 4 b to the rotating shaft 37 b.

The power converging unit 6B has a converging function instead of adividing function of the above-mentioned power-dividing unit 6. Thepower converging unit 6B serves to converge the rotational power fromthe rotating shaft 9 b and the rotational power from the fluid coupling20 on the rotating shaft 37 b.

A power line via the rotating shaft 4 b serves as a power line Rb1, anda power line via the rotating shaft 9 b serves as a power line Rb2.

Operation of the transmission apparatus 15B having the above-mentionedstructure will be described below.

First, a rotational power having a torque Ti and a rotational speed ωiis transmitted from the motor A1 serving as a drive source to therotating input shaft 15 b and the ring gear 35 b of the differentialplanetary gear unit 30B via the input-side clutch 3. The rotationalpower transmitted to the ring gear 35 b is divided into two anddistributed to the carrier 13 b and the sun gear 31 b. The dividedrotational powers are transmitted to the rotating shaft 9 b of the powerline Rb2 and the rotating shaft 4 b of the power line Rb1. Therotational power transmitted to the rotating shaft 4 b is changed inspeed and torque by the fluid coupling 20 and transmitted to therotating shaft 37 b serving as an input shaft of the power convergingunit 6B.

On the other hand, the rotational power from the rotating shaft 9 b isalso transmitted to the rotating shaft 37 b where the power line Rb2 andthe power line Rb1 are joined together and transmitted to the fluidmachinery A2 via the output-side clutch 39. At this time, the rotationalpower transmitted to the fluid machinery A2 has a rotational speed ωoand a torque To. Assuming that there is no power transmission loss inthe transmission apparatus 15B, the following relation holds:ωi×Ti=ωo×To

In this manner, the rotational power from the motor A1 is divided intotwo and distributed to the power line Rb1 passing through the fluidcoupling 20 and the branched power line Rb2, and the divided rotationalpowers are joined together again by the power converging unit 6B, sothat the transmission apparatus 15B transmits the rotational powerbeyond the rotational power limit of the fluid coupling 20.

FIG. 7 shows a third embodiment of the present invention. Those partswhich are different from those of the first embodiment shown in FIG. 1will be mainly described below. Those parts which are denoted by thesame reference numerals as those shown FIG. 1 have identical structureand function.

In FIG. 7, a transmission apparatus 15C is disposed between a motor A1(expressed as a drive unit A1 in FIG. 7) serving as a drive source and afluid machinery A2 (expressed as a rotary machine A2 in FIG. 7) servingas a driven unit. The transmission apparatus 15C is coupled to the motorA1 and the fluid machinery A2 via an input-side clutch 3 and anoutput-side clutch 39.

The transmission apparatus 15C comprises a power-dividing unit 6, afluid coupling 20 for speed change, and a differential planetary gearunit 30, each of which serves as an essential part thereof.

The power-dividing unit 6 distributes a rotational power of a rotatinginput shaft 15 c connected to the input-side clutch 3 to a rotatingshaft 9 c, which is connected to the rotating input shaft 15 c, and to arotating shaft 4 c via gears 7 and 8. A power line via the rotatingshaft 4 c serves as a power line Rc1, and a power line via the rotatingshaft 9 c serves as a power line Rc2.

The fluid coupling 20 is constructed so as to transmit the power fromthe rotating shaft 4 c to the rotating shaft 5 c.

The differential planetary gear unit 30 comprises a sun gear 31, piniongears 33, and a ring gear 35, as with a known structure. The sun gear 31connected to the rotating shaft 9 c, and a carrier 13 c which couplesthe rotating shaft 5 c to the pinion gears 33 via the gear 12 c serve asinput shafts, respectively, and the ring gear 35 serves as an outputshaft. The ring gear 35 is connected to the fluid machinery A2 via theoutput-side clutch 39.

Operation of the transmission apparatus 15C having the above-mentionedstructure will be described below.

First, a rotational power having a torque Ti and a rotational speed ωiis transmitted from the motor A1 serving as a drive source to therotating input shaft 15 c of the transmission apparatus 15C via theinput-side clutch 3. The rotating input shaft 15 c transmits therotational power to the power-dividing unit 6. The power-dividing unit 6distributes the rotational power to the rotating shaft 4 c of the powerline Rc1 and the rotating shaft 9 c of the power line Rc2. At this time,the distribution of the rotational power to the rotating shaft 4 c islimited to such a degree that a torque is below a transmission limitdefined by an absorption capability of the fluid coupling 20 while arotational speed is ωi. The rotational power distributed to the rotatingshaft 9 c has the rotational speed ωi and a residual torque. It ispreferable that the torque to be distributed to the fluid coupling 20 isselected such that an efficient transmission is achieved while thetorque is kept below the transmission limit.

The rotational power of the rotating shaft 9 c is transmitted to the sungear 31 of the differential planetary gear unit 30. On the other hand,the rotational power of the rotating shaft 4 c is changed in speed andtorque by the fluid coupling 20 and transmitted to the carrier 13 c viathe gear 12 c.

The rotational powers transmitted to the sun gear 31 and the carrier 13c are transmitted from the ring gear 35 to the fluid machinery A2 viathe rotating shaft 37 and the output-side clutch 39. At this time, therotational power transmitted to the fluid machinery A2 has a rotationalspeed ωo and a torque To. Assuming that there is no power transmissionloss in the transmission apparatus 15C, the following relation holds:ωi×Ti=ωo×To

In this manner, the rotational power from the motor A1 is divided intotwo and distributed to the power line Rc1 passing through the fluidcoupling 20 and the branched power line Rc2, and the divided rotationalpowers are joined together again by the differential planetary gear unit30, so that the transmission apparatus 15C transmits the rotationalpower beyond the rotational power limit of the fluid coupling 20.

FIG. 8 shows a fourth embodiment of the present invention. Those partswhich are different from those of the first embodiment shown in FIGS. 1and 2 will be mainly described below. Those parts which are denoted bythe same reference numerals as those shown FIGS. 1 and 2 have identicalstructure and function.

In FIG. 8, a transmission apparatus 15D is disposed between a motor A1(expressed as a drive unit A1 in FIG. 8) serving as a drive source and afluid machinery A2 (expressed as a rotary machine A2 in FIG. 8) servingas a driven unit. The transmission apparatus 15D is coupled to the motorA1 and the fluid machinery A2 via an input-side clutch 3 and anoutput-side clutch 39.

The transmission apparatus 15D comprises a power-dividing unit(distribution gears) 6, a fluid coupling 20 for speed change, gear units52 d and 53 d, and a differential planetary gear unit 30, each of whichserves as an essential part thereof.

The power-dividing unit 6 is constructed so as to distribute arotational power of a rotating input shaft 15 d connected to theinput-side clutch 3 to a rotating shaft 4, which is directly connectedto the rotating input shaft 15 d, and a separated rotating shaft 9. Apower line via the rotating shaft 4 serves as a power line Rd1, and apower line via the rotating shaft 9 serves as a power line Rd2.

The fluid coupling 20 is constructed so as to transmit the power fromthe rotating shaft 4 to the rotating shaft 5.

The gear unit 52 d for increasing or decreasing a rotational speed isprovided on the rotating shaft 9 and is coupled to the differentialplanetary gear unit 30 via a rotating shaft 9 d. The gear unit 53 d forincreasing or decreasing a rotational speed is provided on the rotatingshaft 4 and is coupled to the differential planetary gear unit 30 via arotating shaft 5 d.

Change gear ratios of the gear units 52 d and 53 d are set such that arotational speed to be input to the fluid machinery A2 via thedifferential planetary gear unit 30 allows the fluid machinery A2 to beoperated at a maximum efficiency.

The differential planetary gear unit 30 is constructed such that therotating shaft 9 d and the rotating shaft 5 d serve as the input shaftsand the rotational powers of these input shafts are converged andtransmitted to the rotating shaft 37 d. The rotating shaft 37 d isconnected to the fluid machinery A2 via the output-side clutch 39.

Other components are the same as those of the first embodiment.

Operation of the transmission apparatus 15D having the above-mentionedstructure will be described below.

First, a rotational power having a torque Ti and a rotational speed ωiis transmitted from the motor A1 serving as a drive source to therotating input shaft 15 d of the transmission apparatus 15D via theinput-side clutch 3. The rotating input shaft 15 d transmits therotational power to the power-dividing unit 6. The power-dividing unit 6distributes the rotational power to the rotating shaft 4 of the powerline Rd1 and the rotating shaft 9 of the power line Rd2. At this time,the distribution of the rotational power to the rotating shaft 4 islimited to such a degree that a torque is below a transmission limitdefined by an absorption capability of the fluid coupling 20 while arotational speed is ωi. The rotational power distributed to the rotatingshaft 9 has the rotational speed ωi and a residual torque if thepower-dividing unit 6 has a gear ratio of 1. It is preferable that thetorque to be distributed to the fluid coupling 20 is selected such thatan efficient transmission is achieved while the torque is kept below thetransmission limit.

The rotational power of the rotating shaft 9 is increased or decreasedin speed by the gear unit 52 d and transmitted to the differentialplanetary gear unit 30. On the other hand, the rotational power of therotating shaft 4 is changed in speed and torque by the fluid coupling20, and is further increased or decreased in speed by the gear unit 53 dand transmitted to the differential planetary gear unit 30.

In the differential planetary gear unit 30, the rotating shaft 9 d andthe rotating shaft 5 d serve as the input shafts, and the rotationalpowers of these input shafts are converged and transmitted to therotating shaft 37 d.

The rotational power is transmitted from the rotating shaft 37 d to thefluid machinery A2 via the output-side clutch 39. At this time, therotational power has a rotational speed ωo and a torque To. Assumingthat there is no power transmission loss in the transmission apparatus15D, the following relation holds: ωi×Ti=ωo×To

In this manner, the rotational power from the motor A1 is divided intotwo and distributed to the power line Rd1 passing through the fluidcoupling 20 and the branched power line Rd2. The rotational speeds ofthe power line Rd1 and the power line Rd2 are changed such that therotational speed to be input to the fluid machinery A2 allows the fluidmachinery A2 to be operated at a maximum efficiency. The power line Rd1and the power line Rd2 are joined together again by the differentialplanetary gear unit 30. Thus, the transmission apparatus 15D transmitsthe rotational power beyond the rotational power limit of the fluidcoupling 20.

FIG. 9 shows a fifth embodiment of the present invention. Those partswhich are different from those of the first embodiment shown in FIGS. 1and 2 will be mainly described below. Those parts which are denoted bythe same reference numerals as those shown FIGS. 1 and 2 have identicalstructure and function.

In FIG. 9, a transmission apparatus 15E is disposed between a motor A1(expressed as a drive unit A1 in FIG. 9) serving as a drive source and afluid machinery A2 (expressed as a rotary machine A2 in FIG. 9) servingas a driven unit. The transmission apparatus 15E is coupled to the motorA1 and the fluid machinery A2 via an input-side clutch 3 and anoutput-side clutch 39.

The transmission apparatus 15E comprises a power-dividing unit(distribution gears) 6, a fluid coupling 20 for speed change, a gearunit 54 e, and a differential planetary gear unit 30, each of whichserves as an essential part thereof.

The power-dividing unit 6 distributes a rotational power of a rotatinginput shaft 15 a connected to the input-side clutch 3 to a rotatingshaft 4, which is directly connected to the rotating input shaft 15 a,and a separated rotating shaft 9. A power line via the rotating shaft 4serves as a power line Re1, and a power line via the rotating shaft 9serves as a power line Re2.

The fluid coupling 20 is constructed so as to transmit the power fromthe rotating shaft 4 to the rotating shaft 5.

The rotating shaft 9 is connected to the differential planetary gearunit 30, and the rotating shaft 4 is connected to the differentialplanetary gear unit 30 via the rotating shaft 5.

The differential planetary gear unit 30 is constructed such that therotating shaft 9 and the rotating shaft 5 serve as the input shafts andthe rotational powers of these input shafts are converged andtransmitted to the rotating shaft 37. The rotating shaft 37 is connectedto the fluid machinery A2 via the gear unit 54 e and the output-sideclutch 39. A change gear ratio of the gear unit 54 e is set such thatthe rotational speed to be input to the fluid machinery A2 allows thefluid machinery A2 to be operated at a maximum efficiency.

Other components are the same as those of the first embodiment.

Operation of the transmission apparatus 15E having the above-mentionedstructure will be described below.

First, a rotational power having a torque Ti and a rotational speed ωiis transmitted from the motor A1 serving as a drive source to therotating input shaft 15 a of the transmission apparatus 15E via theinput-side clutch 3. The rotating input shaft 15 a transmits therotational power to the power-dividing unit 6. The power-dividing unit 6distributes the rotational power to the rotating shaft 4 of the powerline Re1 and the rotating shaft 9 of the power line Re2. At this time,the distribution of the rotational power to the rotating shaft 4 islimited to such a degree that a torque is below a transmission limitdefined by an absorption capability of the fluid coupling 20 while arotational speed is ωi. The rotational power distributed to the rotatingshaft 9 has the rotational speed ωi and a residual torque if thepower-dividing unit 6 has a gear ratio of 1. It is preferable that thetorque to be distributed to the fluid coupling 20 is selected such thatan efficient transmission is achieved while the torque is kept below thetransmission limit.

The rotational power of the rotating shaft 9 is transmitted to thedifferential planetary gear unit 30. The rotational power of therotating shaft 4 is changed in speed and torque by the fluid coupling 20and transmitted to the differential planetary gear unit 30.

In the differential planetary gear unit 30, the rotating shaft 9 and therotating shaft 5 serve as the input shafts, and the rotational powers ofthese input shafts are converged and transmitted to the rotating shaft37. The rotational power of the rotating shaft 37 is changed in speed bythe gear unit 54 e so as to allow the fluid unit A2 to be operated at amaximum efficiency, and is transmitted to the fluid machinery A2 via theoutput-side clutch 39. At this time, the rotational power transmitted tothe fluid machinery A2 has a rotational speed ωo and a torque To.Assuming that there is no power transmission loss in the transmissionapparatus 15E, the following relation holds: ωi×Ti=ωo×To

In this manner, the rotational power from the motor A1 is divided intotwo and distributed to the power line Re1 passing through the fluidcoupling 20 and the branched power line Re2, and the divided rotationalpowers are joined together again by the differential planetary gear unit30. Thus, the transmission apparatus 15E transmits the rotational powerbeyond the rotational power limit of the fluid coupling 20. Further, therotational speed to be input to the fluid machinery A2 is changed by thegear unit 54 e so that the fluid machinery A2 is operated at a maximumefficiency.

FIG. 10 shows a sixth embodiment of the present invention. Those partswhich are different from those of the first embodiment shown in FIGS. 1and 2 will be mainly described below. Those parts which are denoted bythe same reference numerals as those shown FIGS. 1 and 2 have identicalstructure and function.

In FIG. 10, a transmission apparatus 15F is disposed between a motor A1serving as a drive source and a fluid machinery A2 serving as a drivenunit. The transmission apparatus 15F is coupled to the motor A1 and thefluid machinery A2 via an input-side clutch 3 and an output-side clutch39.

The transmission apparatus 15F comprises a power-dividing unit(distribution gears) 6, a fluid coupling 20 for speed change, gear units51 f, 53 f and 55 f, and a differential planetary gear unit 30, each ofwhich serves as an essential part thereof.

The power-dividing unit 6 is constructed so as to distribute arotational power of a rotating input shaft 15 a connected to theinput-side clutch 3 to a rotating shaft 4, which is directly connectedto the rotating input shaft 15 a, and a separated rotating shaft 9. Apower line via the rotating shaft 4 serves as a power line Rf1, and apower line via the rotating shaft 9 serves as a power line Rf2.

The fluid coupling 20 is constructed so as to transmit the power fromthe rotating shaft 4 to the rotating shaft 5.

The gear unit 51 f for increasing or decreasing a rotational speed isprovided on the rotating shaft 9. The rotational power, which isdistributed to the rotating shaft 9 by the distribution gears 6, isincreased or decreased in speed by the gear unit 51 f, and is furthertransmitted to the differential planetary gear unit 30 via a rotatingshaft 9 f. The gear unit 53 f for increasing or decreasing a rotationalspeed is provided on the rotating shaft 5. The rotational power, whichis distributed to the rotating shaft 4 by the distribution gears 6, isincreased or decreased in speed by the gear unit 53 f, and is furthertransmitted to the differential planetary gear unit 30 via a rotatingshaft 5 f.

The differential planetary gear unit 30 is constructed such that therotating shaft 9 f and the rotating shaft 5 f serve as the input shaftsand the rotational powers of these input shafts are converged andtransmitted to the rotating shaft 37. The rotating shaft 37 is connectedto the fluid machinery A2 via the gear unit 55 f for increasing ordecreasing the rotational speed and the clutch 39.

Change gear ratios of the gear units 51 f, 53 f and 55 f are set suchthat the fluid machinery A2 is operated at a maximum efficiency.

Other components are the same as those of the first embodiment.

Operation of the transmission apparatus 15F having the above-mentionedstructure will be described below.

First, a rotational power having a torque Ti and a rotational speed ωiis transmitted from the motor A1 serving as a drive source to therotating input shaft 15 a of the transmission apparatus 15F via theinput-side clutch 3. The rotating input shaft 15 a transmits therotational power to the power-dividing unit 6. The power-dividing unit 6distributes the rotational power to the rotating shaft 4 of the powerline Rf1 and the rotating shaft 9 of the power line Rf2. At this time,the distribution of the rotational power to the rotating shaft 4 islimited to such a degree that a torque is below a transmission limitdefined by an absorption capability of the fluid coupling 20 while arotational speed is ωi. The rotational power distributed to the rotatingshaft 9 has the rotational speed ωi and a residual torque if thepower-dividing unit 6 has a gear ratio of 1. It is preferable that thetorque to be distributed to the fluid coupling 20 is selected such thatan efficient transmission is achieved while the torque is kept below thetransmission limit.

The rotational power of the rotating shaft 9 is increased or decreasedin speed by the gear unit 51 f and transmitted to the differentialplanetary gear unit 30. On the other hand, the rotational power of therotating shaft 4 is changed in speed and torque by the fluid coupling20, and is further increased or decreased in speed by the gear unit 53 fand transmitted to the differential planetary gear unit 30.

In the differential planetary gear unit 30, the rotating shaft 9 f andthe rotating shaft 5 f serve as the input shafts, and the rotationalpowers of these input shafts are converged and transmitted to therotating shaft 37.

The rotational power of the rotating shaft 37 is changed in speed by thegear unit 55 f so as to allow the fluid unit A2 to be operated at amaximum efficiency, and is transmitted to the fluid machinery A2 via theoutput-side clutch 39. At this time, the rotational power has arotational speed ωo and a torque To. Assuming that there is no powertransmission loss in the transmission apparatus 15F, the followingrelation holds: ωi×Ti=ωo×To

In this manner, the rotational power from the motor A1 is divided intotwo and distributed to the power line Rf1 passing through the fluidcoupling 20 and the branched power line Rf2, and the divided rotationalpowers are joined together again by the differential planetary gear unit30, so that the transmission apparatus 15F transmits the rotationalpower beyond the rotational power limit of the fluid coupling 20.Further, the rotational speed to be input to the fluid machinery A2 ischanged by the gear units 51 f, 53 f and 55 f so that the fluidmachinery A2 is operated at a maximum efficiency.

FIG. 11 shows a seventh embodiment of the present invention. Those partswhich are different from those of the first embodiment shown in FIGS. 1and 2 will be mainly described below. Those parts which are denoted bythe same reference numerals as those shown FIGS. 1 and 2 have identicalstructure and function.

In FIG. 11, a transmission apparatus 15G is disposed between a motor A1(expressed as a drive unit A1 in FIG. 11) serving as a drive source anda fluid machinery A2 (expressed as a rotary machine A2 in FIG. 11)serving as a driven unit. The transmission apparatus 15G is coupled tothe motor A1 and the fluid machinery A2 via an input-side clutch 3 andan output-side clutch 39.

The transmission apparatus 15G comprises a differential planetary gearunit 30, a fluid coupling 20 for speed change, gear units 51 g, 52 g and53 g, and a power converging unit (joining gears) 6B, each of whichserves as an essential part thereof.

The gear unit 51 g for increasing or decreasing a rotational speed isprovided on the rotating input shaft 15 a connected to the input-sideclutch 3. The rotational power, which is transmitted to the rotatinginput shaft 15 a, is increased or decreased in speed by the gear unit 51g, and is further transmitted to the differential planetary gear unit 30via a rotating shaft 4 g.

The differential planetary gear unit 30 is constructed so as todistribute the rotational power of the rotating shaft 4 g to a rotatingshaft 8 g and a rotating shaft 5 g.

The gear unit 52 g for increasing or decreasing a rotational speed isprovided on the rotating shaft 8 g. The rotational power, which isdistributed to the rotating shaft 8 g by the differential planetary gearunit 30, is increased or decreased in speed by the gear unit 52 g, andis further transmitted to one of input shafts of the power convergingunit 6B via a rotating shaft 9 g. The gear unit 53 g for increasing ordecreasing a rotational speed is provided on the rotating shaft 5 g, andis coupled to the fluid coupling 20 via a rotating shaft 6 g. The fluidcoupling 20 is connected to the other of the input shafts of the powerconverging unit 6B via a rotating shaft 37 g.

A power line via the fluid coupling 20 serves as a power line Rg1, and apower line via the rotating shaft 9 g serves as a power line Rg2.

The power converging unit 6B is constructed so as to converge therotational powers from the rotating shaft 9 g and the rotating shaft 37g and transmit the converged rotational power to the output-side clutch39.

Change gear ratios of the gear units 51 g, 52 g and 53 g are set suchthat the rotational speed to be input to the fluid machinery A2 allowsthe fluid machinery A2 to be operated at a maximum efficiency.

Other components are the same as those of the first embodiment.

Operation of the transmission apparatus 15G having the above-mentionedstructure will be described below.

First, a rotational power having a torque Ti and a rotational speed ωiis transmitted from the motor A1 serving as a drive source to therotating input shaft 15 a of the transmission apparatus 15G via theinput-side clutch 3. The rotational speed of the rotating input shaft 15a is increased or decreased by the gear unit 51 g, and the rotationalpower transmitted to the rotating input shaft 15 a is transmitted to thedifferential planetary gear unit 30 via the gear unit 51 g.

The differential planetary gear unit 30 distributes the rotational powerof the rotating input shaft 15 a to the rotating shaft 5 g of the powerline Rg1 and the rotating shaft 8 g of the power line Rg2. At this time,a torque of the rotational power to be distributed to the rotating shaft5 g is limited to a level below a transmission limit defined by anabsorption capability of the fluid coupling 20, and a residual torque isdistributed to the rotating shaft 8 g. It is preferable that therotational power to be distributed to the fluid coupling 20 is adjustedby the gear unit 53 g such that an efficient transmission is achievedwhile the rotational speed and the torque are kept below thetransmission limit.

The rotating shaft 8 g transmits the torque to the power converging unit6B via the gear unit 52 g and the rotating shaft 9 g, and the rotatingshaft 5 g transmits the torque to the power converging unit 6B via thegear unit 53 g, the rotating shaft 6 g, and the fluid coupling 20.

In the power converging unit 6B, the rotational powers of the rotatingshaft 9 g and the rotating shaft 37 g are converged into one rotationalpower, which is transmitted to the fluid machinery A2 via theoutput-side clutch 39. At this time, the rotational power has arotational speed ωo and a torque To. Assuming that there is no powertransmission loss in the transmission apparatus 15G, the followingrelation holds: ωi×Ti=ωo×To

In this manner, the rotational power from the motor A1 is changed inspeed by the gear unit 51 g so as to meet a performance of thedifferential planetary gear unit 30, and is divided into two anddistributed to the power line Rg1 passing through the fluid coupling 20and the power line Rg2. The power line Rg1 and the power line Rg2 areconverged again by the power converging unit 6B. Thus, the transmissionapparatus 15G transmits the rotational power beyond the rotational powerlimit of the fluid coupling 20. Further, the rotational speed to beinput to the fluid machinery A2 is changed by the gear units 52 g and 53g so as to allow the fluid machinery A2 to be operated at a maximumefficiency.

Advantages of the transmission apparatus according to the presentinvention shown in FIGS. 1 through 11 are listed below.

(1) The rotational power beyond the transmission limit of the joint unitis not input to the joint unit, and hence the rotational power can betransmitted efficiently. Further, the fluid coupling can absorb variouskinds of vibrations and impacts such as pulsation of the inputrotational power, shock due to speed change, and torsion vibration ofthe shaft, thus enabling a smooth transmission of the power.(2) The input power is divided into two by the differential planetarygear unit, so that one of the divided powers, which is below thetransmission limit, is distributed to the fluid coupling and the otheris directly distributed to the dividing unit. Accordingly, thetransmission apparatus can transmit the power beyond the transmissionlimit of the fluid coupling.(3) The gear unit is provided on the power line so that the rotationalspeed to be transmitted to the fluid machinery is changed while keepingthe rotational power of the drive source constant. With this structure,an efficiency of the fluid machinery can be optimized.

FIG. 12 shows an eighth embodiment. In FIG. 12, an output shaft 60 of adrive unit, e.g., an electric motor M, is coupled to a first gear 61constituting a dividing unit 6. The first gear 61 is in mesh with asecond gear 62 of the dividing unit 6.

The dividing unit 6 has a first output shaft 63 serving as a rotatingshaft of the first gear 61. This first output shaft 63 is connected to asun gear 64 of a second differential planetary gear unit P2. A carrier66 of planetary gears 65 of the differential planetary gear unit P2 iscoupled to a gear 67 meshing with a gear 68 that is coupled to an outputshaft 69 of a small-capacity variable-speed motor 70. A ring gear 71 ofthe second differential planetary gear unit P2 is connected to an outputshaft 72.

In this example shown in FIG. 12, the output shaft 60 of the drive unitM is connected to the sun gear 64 via the output shaft 63, and arotational power of the variable-speed motor 70 is transmitted to theplanetary gears 65. Although the ring gear 71 is connected to the outputshaft 72, connection arrangement can be made freely. For example, theoutput shaft 63 may be connected to the ring gear 71 or the carrier 66,or the output shaft 69 of the variable-speed motor 70 may be connectedto the sun gear 64 or the ring gear 71. Further, the output shaft 72 maybe connected to the sun gear 64 or the carrier 66.

Specifically, when practicing the present invention, the connectionarrangement of three rotating parts of the differential planetary gearunit can be selected freely. Therefore, in the case of not specifyingthe gear, the three rotating parts will be referred to as a firstrotating element, a second rotating element, and a third rotatingelement.

An output shaft 73 of the second gear 62 of the dividing unit 6 isconnected to a gear 74, and this gear 74 meshes with a gear 75 coupledto the carrier 77 of the planetary gears 76 of a first differentialplanetary gear unit P1.

The output shaft 72 of the second differential planetary gear unit P2 isconnected to the sun gear 78 of the first differential planetary gearunit P1, and a ring gear 79 of the first differential planetary gearunit P1 is coupled to a load L such as a fluid machinery via an outputshaft 80.

Therefore, a rotational power of the output shaft 60 of the drive unit Mis distributed to the output shaft 63 of the first gear 61 and theoutput shaft 73 of the second gear 62 by the dividing unit 6. Theplanetary gears 65 of the second differential planetary gear unit P2 arerotated by the rotation of the variable-speed motor 70, and hence therotational speed of the ring gear 71 is changed according to therotational speed of the planetary gears 65. In this manner, as therotational speed of the output shaft 72 of the second differentialplanetary gear unit P2 is changed, the rotational speed of the sun gear78 of the first differential planetary gear unit P1 is also changed. Asa result, the rotational speed of the output shaft 80 of the firstdifferential planetary gear unit P1 can be changed, and hence therotational speed of the load L can be controlled.

FIG. 13 shows a ninth embodiment of the present invention. An outputshaft 60 of a drive unit M is connected to a first rotating element of afirst differential planetary gear unit P1, and is also connected to asecond rotating element, which mainly transmits a power, of the firstdifferential planetary gear unit P1. A first output shaft 81 is adirect-coupling shaft and is connected to a second gear 82 of aconverging unit 6B. A second output shaft 83, which is connected to athird rotating element of the first differential planetary gear unit P1,is a speed-change shaft and is connected to a first rotating element ofthe second differential planetary gear unit P2.

A second rotating element of this second differential planetary gearunit P2 is connected to an output shaft 69 serving as a motor shaft of asmall-capacity variable-speed motor 70. Further, a third rotatingelement of the second differential planetary gear unit P2 is connectedto a first gear 84 meshing with the second gear 82 of the convergingunit 6B. An output shaft 85 of the converging unit 6B, i.e., a shaft ofthe first gear 84, is connected to the load L.

In this embodiment shown in FIG. 13 also, most of the rotational powerof the drive unit M is transmitted from the output shaft 81, whichserves as a direct-coupling shaft connected to the second rotatingelement of the first differential planetary gear unit P1, to the load Lvia the dividing unit 6. A rotational speed of the third rotatingelement of the first differential planetary gear unit P1 is changedaccording to the rotational speed of the variable-speed motor 70, i.e.,the rotational speed of the second output shaft 83 serving as aspeed-change shaft. As a result, the rotational speed of the firstoutput shaft 81 is changed.

FIG. 14 shows a tenth embodiment of the present invention. An exampleshown in FIG. 14 is a modification of the eighth embodiment shown inFIG. 12, and corresponding parts are denoted by the same referencenumerals. Only different parts will be described below.

In the example shown in FIG. 14, a clutch 90 is provided on an outputshaft 72 of the second differential planetary gear unit P2. An outputshaft 69 of the variable-speed motor 70 is connected to the seconddifferential planetary gear unit P2 via a speed-increasing gear unit 91having a direct-coupling switch clutch (not shown). Further, a clutch 92is provided on an output shaft 73.

In this example, the clutches 90 and 92 are disengaged, and thedirect-coupling switch clutch is switched to the speed-increasing side.Then, the variable-speed motor 70 starts the drive unit such as asquirrel-cage induction motor. When the drive unit M is increased to apredetermined rotational speed, the drive unit M is energized. Accordingto such an operation manner, electric power for the starting can besmall.

In the eight through tenth embodiments also, the rotational powerstransmitted via the direct-coupling shafts (output shafts) 73 and 81 arelarger than the rotational powers transmitted via the speed-changeshafts 72 and 83, respectively. Accordingly, even if the seconddifferential planetary gear unit P2 and the variable-speed motor 70 eachconstituting the joint unit have a small capacity, it is possible toappropriately change the rotational speed of the load L having a largecapacity.

However, when practicing the present invention, if a negative rotationalpower is transmitted to the speed-change shafts 72 and 83, i.e., iffeedback occurs, the rotational power to be transmitted to thedirect-coupling shafts 73 and 81 becomes large by the same amount.Therefore, it is important in designing the transmission apparatus toprevent the feedback from occurring at any rotational speed.

FIGS. 15 and 16 show an eleventh embodiment which is a modification ofthe eighth embodiment. As with the FIG. 14, those parts corresponding tothose in FIG. 12 are denoted by the same reference numerals, and onlydifferent parts will be described below.

In an example shown in FIGS. 15 and 16, a clutch 90 is provided on theoutput shaft 72 of the second differential planetary gear unit P2, i.e.,a speed-change shaft. The variable-speed motor 70 is controlled by aninverter controller 100. When the load L is decelerated, thevariable-speed motor 70 is utilized as a generator and supplies currentto a work W, whereby the variable-speed motor 70 is utilized as a brake,as described later. As with the example shown in FIG. 14, a clutch 92 isprovided on the direct-coupling shaft 73. A reference sign S in thedrawing represents a rotation sensor of the load L.

When the variable-speed motor 70 is utilized as a brake, the work W canbe applied to a variety of actions such as heat generation due toresistance, storing electricity to a storage battery, and sellingelectricity to a commercial power source through a frequency inverter.

Operation will be described with reference to FIG. 16. A controller unit(not shown) receives a signal from the rotation sensor S and then sendsa switching signal to the inverter controller 100 for the work W.

First, the control unit reads the signal from the rotational sensor S(step S1), and decides whether or not the load L is decelerated (stepS2). In the case of NO in step S2, then the variable-speed motor 70 isused as a motor (step S3), and the control unit decides whether or notthe control is finished (step S6). If the control is not finished, thenthe process proceeds to step S1. If the control is finished, then theoperation is finished.

In the case of YES in step S2, i.e., when the load L is decelerated, thecontrol unit stops the supply of the electric power to thevariable-speed motor 70 and switches connection of the variable-speedmotor 70 to the work W (step S4). As a result, the variable-speed motor70 acts as a generator to perform braking (step S5). Then, whether thecontrol is finished or not is decided (step S6).

FIG. 17 shows a modification of the embodiment shown in FIG. 12. In theembodiment shown in FIG. 17, the direct-coupling shaft 73 is coupled tothe first rotating element of the first differential planetary gear unitP1 via a first speed-increasing or speed-decreasing gear 101. The outputshaft 72 of the second differential planetary gear unit P2 is coupled tothe second rotating element of the first differential planetary gearunit P1 via a second speed-increasing or speed-decreasing gear 102. Thethird rotating element of the first differential planetary gear unit P1is coupled to the load L via a third speed-increasing orspeed-decreasing gear 103 and the output shaft 80.

Since the speed-increasing or speed-decreasing gears 101 through 103 areprovided as described above, distribution of power flow can be optimizedand operation manner of the load L can be diversified.

According to the transmission apparatus of the present invention shownin FIGS. 12 through 17, because the joint unit is constituted by acombination of the second differential planetary gear unit and thevariable-speed motor, a smooth speed-change operation can be performedby changing the speed of the variable-speed motor. Further, because therotational power can be transmitted mainly via the coupling shaftserving as the direct-coupling shaft coupling the first differentialplanetary gear unit and the dividing unit, the capacity of the seconddifferential planetary gear unit and the variable-speed motor as thejoint unit can be small. As a result, it is possible to provide atransmission apparatus which can perform an efficient speed-changeoperation with small impact.

INDUSTRIAL APPLICABILITY

The present invention is suitable for use in a transmission apparatushaving at least one of a dividing unit and a differential planetary gearunit and having a joint unit.

1. A transmission apparatus comprising: a dividing unit; a differentplanetary gear unit; and a fluid coupling; wherein a rotational powerwhich has been input to said transmission apparatus is transmitted tosaid dividing unit via a single input shaft and is output to tworotating shafts; wherein one of said two rotating shafts is coupled toone of two input shafts of said differential planetary gear unit;wherein the other of said two rotating shafts is coupled to the other ofsaid two inputs shafts of said differential planetary gear unit via saidfluid coupling; wherein one of two rotational powers that have beenoutput to said two rotating shafts is transmitted via said fluidcoupling, and is smaller than the other of the two rotational powers;wherein the rotational power transmitted via said fluid coupling issmaller than the rotational power which has been input to saidtransmission apparatus; wherein said fluid coupling has a scoop tubedisposed either at a power input side or at a power output side of saidfluid coupling; wherein the rotational power which has been input tosaid transmission apparatus is transmitted to said differentialplanetary gear unit via a single input shaft and is transmitted to twooutput shafts of said differential planetary gear unit; wherein one ofsaid two output shafts of said differential planetary gear unit isconnected to one of two input shafts of a converging unit; and whereinthe other of said two output shafts of said differential planetary gearunit is connected to the other of said two input shafts of saidconverging unit via said fluid coupling.
 2. A transmission apparatuscomprising: a dividing unit to which a rotational power from a driveunit is transmitted; a joint unit; and a first differential planetarygear unit; wherein one rotational power to be transmitted via said jointunit is smaller than the other rotational power, and said joint unitcomprises an electric motor and a second differential planetary gearunit.
 3. A transmission apparatus comprising: at least one of a dividingunit and a first differential planetary gear unit; and a joint unit;wherein a rotational power from a drive unit is divided into at leasttwo rotational powers by said dividing unit or said first differentialplanetary gear unit, one of the rotational powers is input to said jointunit, the rotational power to be input to said joint unit is smallerthan the other of the rotational powers, and said joint unit comprisesan electric motor and a second differential planetary gear unit.
 4. Atransmission apparatus according to claim 2 or 3, wherein: saidtransmission apparatus comprises both said dividing unit and said firstdifferential planetary gear unit; the rotational power from said driveunit is transmitted to said dividing unit via a single input shaft ofsaid dividing unit and is output from said dividing unit to two rotatingshafts; one of said two rotating shafts is connected to one of two inputshafts of said first differential planetary gear unit; and the other ofsaid two rotating shafts is connected to the other of said two inputshafts of said first differential planetary gear unit.
 5. A transmissionapparatus according to claim 2 or 3, wherein: the rotational power fromsaid drive unit is transmitted to a single input shaft of said firstdifferential planetary gear unit; one of two output shafts of said firstdifferential planetary gear unit is connected to one of two input shaftsof a converging unit; and the other of said two output shafts of saidfirst differential planetary gear unit is connected to the other of saidtwo input shafts of said converging unit via said second differentialplanetary gear unit.
 6. A transmission apparatus according to claim 2,wherein: said second differential planetary gear unit has asingle-pinion-type structure in which one planetary gear is arranged ina radial direction and one or more planetary gears are arranged in acircumferential direction in a region between a sun gear and a ringgear; and each of said drive unit, said electric motor, and a load isdirectly connected to any one of an input shaft, an output shaft, and aspeed-change shaft.